(a) Technical Field of the Invention
The present invention relates to a positioning structure of the transmission device of a screw fastening apparatus, and in particular, the positioning device preventing the screw from shaking until, the screw is pushed in.
(b) Description of the Prior Art
FIGS. 1, 2 and 3 disclose conventional screw fastening apparatus including a securing seat A, a rotating screw shaft B, a mobile seat C, a positioner D and a transmission device E. A power element (not shown) is used to drive the screw shaft B. If screw F1 is to be pushed into an article I, the positioner D has to press onto the article. When the screw F1 is locked to the article I, the positioner D is then removed. The drawback of the conventional fastening device is that the gear E11 on the gear body E1 cannot hold the weight of the screw F1 and therefore the screw F1 will shake before it is fastened. Thus the screw F1 cannot be precisely locked to a positioning point to allow the screw shaft B to push in the screw F1.